Depth of organ response in AL amyloidosis is associated with improved survival: new proposed organ response criteria

Peripheral Nervous, Hepatic, and Gastrointestinal Endpoints for AL Amyloidosis Clinical Trials: Report from the Amyloidosis Forum Multi-organ System Working Group

Systemic immunoglobulin light chain (AL) amyloidosis is a heterogeneous rare disease driven by a destructive monoclonal gammopathy and typified by misfolded immunoglobulin light and/or heavy chains which aggregate and deposit in organs as insoluble amyloid fibrils. Disease heterogeneity is driven by the degree of multi-systemic involvement; cardiac, renal, neurological, and gastrointestinal (GI) systems are affected to varying degrees in different patients. While prognosis is primarily driven by hematologic response to treatment and outcomes associated with cardiac events and overall survival, the involvement of the peripheral nervous, hepatic, and GI systems can also have a significant impact on patients. The Amyloidosis Forum ( https://amyloidosisforum.org ) is a public-private partnership between the nonprofit Amyloidosis Research Consortium ( www.arci.org ) and the US Food and Drug Administration (FDA) Center for Drug Evaluation and Research formed to advance drug development for the treatment of systemic amyloid disorders. A series of virtual workshops focused on the development of novel, patient-relevant endpoint components and analytical strategies for clinical trials in AL amyloidosis. This review summarizes the proceedings and recommendations of the Multi-Systemic Working Group which identified, reviewed, and prioritized endpoints relevant to the impacts of AL amyloidosis on the peripheral nervous, hepatic, and GI systems. The Working Group comprised amyloidosis experts, patient representatives, statisticians, and representatives from the FDA, Medicines and Healthcare products Regulatory Agency (MHRA), and pharmaceutical companies. Prioritized neuropathy/autonomic endpoints included a modified form of the Neuropathy Impairment Score (NIS + 7) and the Composite Autonomic Symptom Score (COMPASS-31), respectively. Alkaline phosphatase was identified as the most relevant indicator of liver involvement and disease progression. Following extensive review of potential GI endpoints, the Working Group identified multiple exploratory endpoints. These recommended components will be further explored through evaluation of clinical trial datasets and possible integration into composite endpoint analysis.

Clinical characteristics and prognostic value of renal immune complex deposition in patients with light chain amyloidosis

Although patients with light chain amyloidosis (AL) may present with co-deposition of amyloid and immune complexes (ICs) in renal biopsies, data on clinical characteristics and prognostic value of renal IC deposition are limited. A total of 73 patients with AL amyloidosis who were newly diagnosed by renal biopsy in Xijing Hospital (Xi'an, China) were divided into two groups (IC and non-IC groups). As a result, renal IC deposition was found in 26% of patients. Patients with IC deposition were associated with more urinary protein excretion and lower serum albumin. Notably, patients in the non-IC group achieved higher hematological overall response rate (81.5% vs. 47.4%, p = 0.007) and ≥VGPR rate (75.9% vs. 39.8%, p = 0.004) compared with those in IC group. Renal response rate was also higher in the non-IC group (63% vs. 31.6%, p = 0.031). With the median follow-up time of 19 months, a significantly worse overall survival was observed in patients with the IC group as compared with those without renal IC deposition in the Kaplan-Meier analysis (p = 0.036). Further multivariate analysis demonstrated that renal immune complex deposition was associated with worse overall survival in patients with AL amyloidosis (HR 5.927, 95% CI 2.148-16.356, p = 0.001).

Prognostic Implication of Longitudinal Changes of Left Ventricular Global Strain After Chemotherapy in Cardiac Light Chain Amyloidosis

Aim

Cardiac involvement is the main prognostic determinant in AL amyloidosis. We sought to determine the prognostic significance of longitudinal change of left ventricular (LV) global longitudinal strain (GLS) in cardiac light chain (AL) amyloidosis patients undergoing chemotherapy.

Methods and Result

We retrospectively investigated 117 cardiac AL amyloidosis patients who underwent chemotherapy from 2005 to 2019. All patients underwent comprehensive 2D conventional transthoracic echocardiography at baseline and after completion of first-line chemotherapy. Speckle tracking analysis of images was performed offline. Absolute value of LV GLS was expressed as [LV GLS] and change of [LV GLS] after chemotherapy was expressed as Δ [LV GLS]. Clinical outcomes including cardiac response and all-cause mortality were analyzed.

Baseline clinical and echocardiographic parameters were similar in patients with and without CR. Δ [LV GLS] significantly differed between the CR and non-CR groups (0.4 ± 2.8% in the CR group vs. −0.6 ± 2.5% in the non-CR group, P-value = 0.046). Δ [LV GLS] showed satisfactory predictive performance for all-cause mortality (cut-off value = 0.8%, AUC 0.643, 95% CI [0.537–0.748]). Adding Δ [LV GLS] to the Mayo stage + pre-chemotherapy [LV GLS] model showed incremental prognostic value (C-index: 0.637 vs. 0.708; Relative Integrated Discrimination Index 0.07, P-value = 0.003; Net Reclassification Improvement 0.54, P-value < 0.001). Δ [LV GLS] showed good correlation with cardiac response (AUC 0.820, 95% CI [0.737–0.904]).

Conclusion

In cardiac amyloidosis patients who underwent chemotherapy, longitudinal change of [LV GLS] after chemotherapy showed significant association with overall survival as well as cardiac response.

Immunoglobulin light chain amyloidosis: 2022 update on diagnosis, prognosis, and treatment

DISEASE OVERVIEW

Immunoglobulin light chain amyloidosis is a clonal, nonproliferative plasma cell disorder in which fragments of immunoglobulin light or heavy chain are deposited in tissues. Clinical features depend on organs involved but can include heart failure with preserved ejection fraction, nephrotic syndrome, hepatic dysfunction, peripheral/autonomic neuropathy, and "atypical smoldering multiple myeloma or monoclonal gammopathy of undetermined significance (MGUS)."

DIAGNOSIS

Tissue biopsy stained with Congo red demonstrating amyloid deposits with apple-green birefringence is required for the diagnosis of AL amyloidosis. Invasive organ biopsy is not required in 85% of patients. Verification that amyloid is composed of immunoglobulin light chains is mandatory. The gold standard is laser capture mass spectroscopy.

PROGNOSIS

N-terminal pro-brain natriuretic peptide (NT-proBNP or BNP), serum troponin T (or I), and difference between involved and uninvolved immunoglobulin free light chain values are used to classify patients into four groups of similar size; median survivals are 73, 35, 15, and 5 months.

THERAPY

All patients with a systemic amyloid syndrome require therapy to prevent deposition of amyloid in other organs and prevent progressive organ failure. Current first-line therapy with the best outcome is daratumumab, bortezomib, cyclophosphamide, and dexamethasone. The goal of therapy is a complete response (CR). In patients failing to achieve this depth of response options for consolidation include pomalidomide, stem cell transplantation, venetoclax, and bendamustine.

FUTURE CHALLENGES

Delayed diagnosis remains a major obstacle to initiating effective therapy prior to the development of end-stage organ failure. Trials of antibodies to catabolize deposited fibrils are underway.

Acquired and inherited amyloidosis: Knowledge driving patients' care

Until recently, systemic amyloidoses were regarded as ineluctably disabling and life-threatening diseases. However, this field has witnessed major advances in the last decade, with significant improvements in therapeutic options and in the availability of accurate and non-invasive diagnostic tools. Outstanding progress includes unprecedented hematological response rates provided by risk-adapted regimens in light chain (AL) amyloidosis and the approval of innovative pharmacological agents for both hereditary and wild-type transthyretin amyloidosis (ATTR). Moreover, the incidence of secondary (AA) amyloidosis has continuously reduced, reflecting advances in therapeutics and overall management of several chronic inflammatory diseases. The identification and validation of novel therapeutic targets has grounded on a better knowledge of key molecular events underlying protein misfolding and aggregation and on the increasing availability of diagnostic, prognostic and predictive markers of organ damage and response to treatment. In this review, we focus on these recent advancements and discuss how they are translating into improved outcomes. Neurological involvement dominates the clinical picture in transthyretin and gelsolin inherited amyloidosis and has a significant impact on disease course and management in all patients. Neurologists, therefore, play a major role in improving patients' journey to diagnosis and in providing early access to treatment in order to prevent significant disability and extend survival.

[Primary generalized AL amyloidosis]

The paper describes an autopsy observation of a 71-year-old male with primary generalized AL amyloidosis lasting about 4 months after its manifestation to the onset of death from hepatic and renal failure. Total damage to the liver and spleen, as well as amyloid deposits in the kidneys, adrenal glands, and pancreas were noted.

Time to Redefine Risk-Stratification and Response Criteria in Immunoglobulin Light Chain Amyloidosis?

Immunoglobulin light chain (AL) amyloidosis results from clonal plasma cell (PC)-derived immunoglobulin light chain-mediated end-organ dysfunction, the extent and severity of which predicts survival. Anti-PC therapies reduce clonal light chain burden, which usually results in improvement of organ function, and consequently overall survival. Response assessment is critical to gauge therapeutic efficacy, to report clinical trial outcomes, and to switch therapy in those without response. Response in AL amyloidosis is 2-fold: hematologic response and organ response (OR). Depth of hematologic response is graded on the basis of serum free light chain (sFLC) parameters, but assessment of OR is binary. The role of normal sFLC ratio or complete remission as a treatment end point has been challenged, thus highlighting the need to quantify involved FLC and residual PC beyond the normal sFLC ratio to possibly account for the ongoing organ damage seen in some patients with complete remission. Mass spectrometry and urinary exosome represent ultrasensitive strategies to estimate involved FLC below the detection threshold of current sFLC assays. The role of new sFLC parameters and minimal residual disease as potential prognostic parameters has been recognized. Brain natriuretic peptide (BNP) and 24-hour proteinuria:estimated glomerular filtration rate ratio were identified to overcome certain limitations of N-terminal-Pro-BNP, 24-hour proteinuria, and estimated glomerular filtration rate for cardiac and renal response assessment, respectively. Use of monoclonal antibodies targeting PC and amyloid deposits has expanded the therapeutic armamentarium of AL amyloidosis, and given their excellent efficacy, early ORs are reported. This review provides insights into recent advances in the risk-stratification and response assessment of patients with AL amyloidosis in light of the changing therapeutic paradigms. Incorporation of these advancements into formal consensus guidelines would require further validation.

Prognosis and Staging of AL Amyloidosis

The treatment options for systemic light chain amyloidosis (AL) are currently widening in an unprecedented way, brought about by an expanding arsenal of anti-myeloma therapy as well as by novel approaches to target toxic light chains and, most recently, deposited amyloid directly. In this context, accurate estimates of prognosis in AL, which allow for reliable patient advice and for example comparison of different therapies, are particularly important to clinicians. Some biomarkers and especially the genetic background of the underlying clonal disease as evaluated by interphase fluorescence in situ hybridization even have predictive value, enabling an appropriate treatment selection. Derived from the most frequently involved organs in AL, heart and kidney, this review focuses on overall survival and renal survival. A comprehensive overview and summary of reported prognostic factors and biomarkers in AL is given and the most important and validated factors are highlighted. Finally, established staging systems in AL as well as validated and perspective response criteria are presented.